A Behavioral Adaptation
What is the Caterpillar Doing . . . and Why?

1) Watch the caterpillar in this short video clip very carefully. What’s going on? Do you notice anything surprising?

2) Describe what you see in detail. The process of writing a good verbal description helps you look closely. Use the vocabulary word “petiole” in your description. (The petiole is the stalk of a leaf. It connects the leaf to the stem of the plant.)

The petiole is the stalk of a leaf.

3) Now watch the clip again. This caterpillar behavior, called “leaf notching,” is an example of a behavioral adaptation.

An "adaptation" is a physical or behavioral feature that evolved gradually over generations and that helps organisms survive or reproduce in particular environments.

Remember, when thinking about adaptations, there's always a WHY behind WHAT you see. So whenever you see an unusual behavior or body part, ask yourself WHY...

WHY, for example, would a caterpillar cut the petiole of the very leaf it's standing on? The leaf looks like a lose tooth, ready to break from the plant!

Journaling Question

  • Why do you think the monarch caterpillar cuts the petiole of a milkweed leaf before it eats the leaf?

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